I agree "evil" is too simplistic, and sets a pretty high bar. The age of consent, and indeed the concept of consent itself, is determined by the norms of a particular society at a particular time, and the law is then set according to those norms. Harris's behaviour deeply offended our society's ideas of what is acceptable, but in some places and at some times it might have seemed unremarkable. His behaviour was compounded by his apparent lack of contrition or concern for his victims. Perhaps "vile" is too strong a word, but I'm struggling to think of an alternative.

Is it a sickness to be cured, or a moral failure to be corrected? I don't know, but in either case the person has to show willingness, which Harris doesn't appear to have done. He died with his well-earned good reputation in tatters, and a trail of people who must have been damaged by his actions.